Images of the Victorian Royal Family
Hemophilia is a genetic disease also termed as 'The Royal disease'
Hemophilia is a genetically inherited blood-clotting disorder caused by the
deficiency of clotting factors. It is characterized by the inability to
properly form blood clots. Due to this,even a minor trauma can lead to profuse
hemorrhage.
The 3 types of Hemophilia are Hemophilia A(max%), Hemophilia
B and Hemophilia C caused by the deficiency of clotting factors VIII, IX, and
XI respectively.
The affected gene is present in the X-chromosome. It can be
passed along generations by hereditary transmission in an X-linked recessive
pattern.
Genotypically, males (XY) have one X and one Y chromosome. Whereas,
females (XX) have two X chromosomes.
Due to the recessive pattern of
inheritance in hemophilia, when children inherit the affected X-chromosome, the affected male
offspring will always express the disease whereas most females act as carriers
of the disease. This is because the carrier females have another copy of X-chromosome
that contains a normal gene aiding the formation of clotting factors. Whereas,
males have only one copy of X-chromosome due to which they always express the
disease if they inherit the affected gene.
The treatment of Hemophilia is mainly by replacement therapy.
The probability of genetic transmission can be better understood using Punnett squares.
Scenario 1: (Carrier mother & Unaffected father)
Unaffected
father
X Y
Carrier mother X
|
XX
|
XY
|
X
|
XX
|
XY
|
The red X denotes
the chromosome carrying the hemophilia gene
XX stands for normal
female
XX stands
for carrier female
XY stands for normal or
unaffected male
XY
stands for affected or haemophilic male
|
Can male offsprings of affected families be exempt from the
disease?
Yes, of course. One can understand this better by studying
the probability of genetic transmission using Punnett squares. (Look at Scenario 1, 2 and 3)
Affected father
X Y
Unaffected
mother
X
|
XX
|
XY
|
X
|
XX
|
XY
|
The red X denotes the chromosome carrying the hemophilia
gene
XX stands
for carrier female
XY stands for normal or unaffected male
Note:
Also look at scenario 1 and 3 for other probabilities of unaffected male
offsprings
|
Also, keep in mind that an affected father can never pass the hemophilia gene to his son as he only passes the Y chromosome. Whereas, daughters of affected fathers always inherit a copy of the affected X chromosome. For this reason, the daughters of affected fathers always become carriers of hemophilia.
Can female offsprings of affected families express the disease?
Yes, that is possible. Find out more with the probable scenario shown in the Punnett square below.
Scenario 3: (Carrier mother & affected father)
Affected father
X Y
Carrier
mother
X
|
XX
|
XY
|
X
|
XX
|
XY
|
The red X denotes
the chromosome carrying the hemophilia gene
XX stands
for carrier female
XX stands
for affected or haemophilic female
XY stands for normal or
unaffected male
XY
stands for affected or haemophilic male
|
Can a female offspring be unaffected i.e., not even be a
carrier?
Yes. Look at scenario 1 to know the probability of a normal
female offspring in an affected family.
Can someone with turner syndrome develop hemophilia?
Turner syndrome is a genetic disorder with a partial or
complete monosomy of the X chromosome. The affected individual has XO genotype
with female phenotype.
A child affected by turner syndrome can develop hemophilia
if the child inherits the affected copy of X chromosome from the affected
father, affected mother or carrier mother.
If the child inherits a copy of the normal gene from the
unaffected mother, carrier mother or unaffected father, then the child with
turner syndrome remains unaffected.
Why is hemophilia called a royal disease?
Queen Victoria, the Queen of England from 1837 to 1901, was a carrier of the hemophilia gene.She had nine children and as English royal family members married into royalty of other countries, the disease eventually passed on to the European royal families of Spain, Russia, Denmark, Austria and Germany. Therefore,hemophilia gained its title of 'The Royal Disease' because it spread through the royal families of Europe through Queen Victoria's descendants.(studyres.com)
What subtype of Hemophilia did the royals have?
Recent DNA studies show that the royal disease was Hemophilia B
How did Queen Victoria get affected by Hemophilia?
The traditional explanation how hemophilia entered the royal family describes a spontaneous mutation in Victoria’s gene or the sperm in her father, Edward Augustus, the Duke of Kent.(studyres.com)
Does anyone in the current royal family have this disease?
Check out this link for the pedigree chart containing an illustrated answer to this question.
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